Wireless power systems may include a power transfer unit (e.g., a charging device) and one or more power receive units (e.g., a cellphone, a laptop, etc.) to be charged. The power receive units may be configured to stop receiving power from the power transfer unit once they are charged. However, a non-compliant object present within a charging region of the power transfer unit may continue to receive power indefinitely. This situation presents a safety hazard because the non-compliant object may dissipate the power it receives as heat, causing damage or personal injury.
The power transfer unit may be configured to detect the presence of the non-compliant object based on an impedance shift caused by the non-compliant object. The power transfer unit may also detect the non-compliant object by comparing an amount of power transmitted to the power receive unit to an amount of power received by the power receive units. However, conventional power transfer units may not be configured to measure power and impedance with sufficient speed and accuracy to correctly detect the non-compliant object. Accordingly, there is a need for improved systems and methods for measuring power and impedance in wireless power charging systems